Even experienced pros make mistakes in the gym. But you don't have to with our comprehensive guide of what not to do

Change your programme after four to six weeks, otherwise you get into a pattern and you stop producing results because your body has hit a plateau

You may be new to the gym, or you may have been going for years, but there are some mistakes that even seasoned trainers make again and again. If you’ve reached a plateau in your training or you’re not getting to where you want to be fast enough, there’s a good chance that you’re making at least one of these mistakes.

Maxim has recruited Lee Archer, personal trainer and director at Pro Fitness in Bristol, to help you avoid the many pitfalls that are waiting to trap unwary gym-goers.

1 You always stick to the same workoutWe all tend to repeat the things we like doing, so it’s no wonder that once we find a workout that suits us we stick to it. Archer advises against this. ‘Change your programme after four to six weeks, otherwise you get into a pattern and you stop producing results because your body has hit a plateau,’ he says. As well as changing your workout, you can mix it up by cross training – try a circuit or kickboxing class once a week.

2 You copy the hardcore gym membersIt’s easy to think that to get as ripped as the guy in your gym who wows all the female instructors with one-armed press-ups, you have simply to follow his lead. ‘People see someone lifting a heavier weight or using a certain technique and rather than ask them what they’re up to they just copy them,’ says Archer. The problem is that without knowing what someone else’s fitness aims are, copying them could land you with unexpected results or an injury. ‘The best solution is to read magazines and do your homework before you hit the gym. Be careful who you take advice from, because some fitness instructors are not highly qualified and won’t necessarily know what is best for you.’

3 You go every dayYou may be someone who can’t do anything by halves, but working out every day is not sustainable – either physically or mentally. ‘If you go every day you won’t be able to maintain a useful intensity and you’ll get bored,’ says Archer. ‘It becomes a chore and you’ll start missing sessions, beating yourself up about it and losing motivation.’ Incorporate proper rest days into your schedule. ‘Take the dog for a walk, or go to the gym but use the sauna and Jacuzzi to chill out,’ he suggests.

4 You use the gym for socialisingGo to your gym often enough and it starts to feel like a second home. This is a dangerous moment. ‘For a lot of people who go every day it becomes their social life,’ says Archer. ‘They chat for half an hour and their training suffers, then they go to the restaurant afterwards and suddenly they’re at the gym every night – but how much work are they actually doing?’ So get your priorities right. The gym is there to burn calories and get you fit and looking good.

5 You exercise aimlesslyExercise is enjoyable for its own sake. But once the high of bashing out monster reps on the bench press wears off it can seem a bit pointless. Keep short-term and long-term goals in mind to keep you motivated, and chart your progress. ‘A short-term goal might be to improve your treadmill speed by a notch. It’s a good way to keep yourself working towards your long-term goal,’ says Archer. ‘If you can’t think of a long-term goal, it’s the gym staff’s job to help you find one.’

6 You only train on your ownSingle-minded focus is commendable, but all top athletes use training partners to keep them going and push them to the next level of performance. ‘Ideally you want someone who’s got the same goals as you and whose strength and fitness levels are just a bit better than yours,’ says Archer. ‘You’ll be pushed in every session and each will make sure the other goes to the gym.’

7 You never take a breakSlavishly following a workout plan for a whole year is likely to lead to burnout. ‘If your training is getting stale and you’re not getting anywhere, take a break – but do it properly and have a couple of weeks off,’ says Archer. ‘It gives you what you need for a total recovery of your body and your mind, because boredom is the biggest killer. If you go on holiday, you don’t have to pack running shoes. Treat it as a way to reward yourself and help you reach your goals.’

8 You beat yourself up when you have a bad sessionEven the most motivated and energetic gym-goer can have a really crap training session. There’s often no real reason: your body just isn’t up for it. Don’t imagine that you’re going backwards. ‘Sometimes you don’t feel great, but just being there is enough,’ says Archer. ‘People who are hard on themselves and start to feel negative about it tend to eventually stop going to the gym altogether.’

9 You confuse a tired brain with a tired bodyA tough day at the office leaves you shattered and in no mood for the gym, so you go home and try to get an early night but end up with a bout of insomnia. If that sounds familiar, you may need to separate mental and physical fatigue. ‘People think they’re tired when all they’ve done is sit at their computers. Their brain is knackered but their body is keyed-up and ready for exercise,’ says Archer. ‘By going to the gym, you’ll get your energy levels surging and de-stress yourself in the process.’

10 You work through coldsIt’s often said that if you exercise when you have the beginnings of a cold, you’ll work it out of your system. This is nonsense. ‘When you train you weaken your immune system because you ask it to repair the muscles you’ve damaged in order for them to get stronger,’ says Archer. ‘If you’ve got a cold already, lowering the immune system is going to bring that cold on even more.’ If you’re feeling ill, eat well and take two days off to recover so you’re fully fit to begin training again.

11 You stick to the machinesYou’ve reached a plateau and are struggling to move that pin on to heavier weights on your favourite machine. But your body knows its limits better than you do and has shut down growth in the muscle group you’re targeting because its supporting stabilising muscles aren’t strong enough. The best way to work stabilisers and make your other muscles work harder at the same time is to replace the weight machine with dumb-bells. ‘You can get a lot more from dumb-bells because their movement is not restricted and they work both sides equally,’ says Archer.

12 You don’t warm up specificallyRunning on a treadmill for ten minutes won’t warm you up for a set of chin-ups. ‘Try matching the warm-up to the muscle group – rowing is good for the upper body. Then do two light sets of 12-15 reps before you do your work sets,’ says Archer. ‘The same applies to cardio workouts. Warm up at 30-60 per cent of race pace.’

13 You don’t time your rests between setsBetween sets, you wander around or sit staring into space until you sense that the guy waiting for your station is getting wound up and you launch into the next set. This is likely to sabotage your workout. ‘Your recovery time is important when looking at how much you are going to be able to lift later on,’ says Archer. ‘Too short a rest and your muscles won’t have recovered; too long and you won’t get the benefit.’ Wear a stopwatch and don’t be intimidated into starting your next set too early.

14 You only ever use heavy weights to build muscleWhen you hit the weights room, you always lift the heaviest weight possible. This may limit your growth because you’ll hit your muscles in a very predictable way, and it’s hard to control large weights precisely. ‘Now and then, go light and do extra reps with a greater range of motion. People don’t always lock out on biceps curls, for instance, and you can end up with short biceps. If you go heavy you have to make sure that your technique is spot-on first,’ says Archer.

15 You do too many workoutsYou hammer yourself into the ground with weights and cardio training until you end up breaking down your body faster than it can repair itself. ‘When I train my clients I go for three or four sessions in the gym a week with three days off within that,’ says Archer. ‘When you rest is when you grow, and people don’t realise how long they have to rest. Listen to your body and if a muscle is aching don’t work it until it stops.’